Australopithecus robustus skull, SK-48 (1.5 to 2 million years).
The Australopithecus robustus skull SK-48 was discovered by Fourie in Swartkrans, South Africa in 1950 and described by R. Broom in 1952. SK-48, formerly called Paranthropus crassidens, greatly increased what is known about australopithecines. The Transvaal cave site where it was found was blasted by explosives but, remarkably, the skull survived. The skull was found with the right canine, the first premolar and all three molars intact. On the basis of the adult teeth and small sagittal crest, Broom determined the specimen to be an adult female. The sagittal crest, large zygomatic arches with relatively small front teeth, and large grinding teeth suggest a robust australopithecine. However, some now are reconsidering a new genus for SK-48.